Spectrally Inverted Fiber Signal Transmission for Nonlinear Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fiber optic communication systems are limited by nonlinear effects such as self-phase modulation (SPM) and cross-phase modulation (XPM), which restrict transmission distance and capacity due to high computation complexity in digital signal processing techniques like digital back propagation (DBP), and the inability to account for adjacent channel interference.
Innovation Solution
A system that transmits two spectrally inverted copies of an information signal over a fiber link, allowing for phase rotation estimation and compensation at the receiver, simplifying digital signal processing and enabling partial or full removal of nonlinear effects with reduced computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital back propagation (DBP) is used to mitigate nonlinear effects, then transmission distance and capacity are improved, but computation complexity becomes extremely large and practically impossible to implement
Solution Approach 1:
The patent divides the single complex DBP problem into two simpler sub-problems by transmitting two spectrally inverted copies of the signal. Each copy experiences opposite nonlinear phase rotation, allowing the system to process two simpler compensation tasks instead of one extremely complex task, thereby reducing overall computation complexity while maintaining transmission performance
Solution Approach 2:
The patent creates two copies of the information signal with spectrally inverted spectra. These copies are transmitted simultaneously through the fiber and both are received and processed. By having two copies with opposite nonlinear effects, the system can average or combine them to cancel nonlinear distortions, achieving mitigation with reduced computational burden compared to full DBP
2Reliability
If optical power is increased to meet required OSNR at the receiver, then transmission distance and throughput are improved, but nonlinear fiber effects convert amplitude modulation into phase modulation causing distortion
Solution Approach 1:
The patent converts the harmful nonlinear phase rotation into a beneficial effect by creating two spectrally inverted signal copies. The nonlinear phase rotation affects each copy in opposite directions, and by processing both copies at the receiver, the system transforms the harmful nonlinear distortion into a canceling effect, allowing higher optical power to be used without proportional increase in distortion
Solution Approach 2:
The patent combines two spectrally inverted signal copies to form a composite transmission system. This composite approach allows the beneficial properties of both signals (opposite nonlinear phase rotations) to work together, creating a system that is more resistant to nonlinear effects than either signal alone, enabling operation at higher power levels
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach extends the reach and capacity of fiber optic communication systems by tolerating nonlinearities, simplifying digital signal processing, and enabling the use of phase-sensitive optical amplifiers, while reducing the computational burden compared to full digital back propagation.
Implementation Method 1
communication over a fiber link
Implementation Method 2
nonlinear fiber effects, such as self-phase modulation, SPM for short and cross-phase modulation, XPM for short
Implementation Method 3
nonlinear fiber effects, such as self-phase modulation, SPM for short and cross-phase modulation, XPM for short
Data Source
AI summary
A system for communication over a fiber link is disclosed. The system comprises a transmitter to transmit an information signal that comprises an information spectrum, and to transmit two spectrally inverted copies of the information spectrum over the predefined length of the fiber link, the two spectrally inverted copies corresponding to a first spectrum with a first center wavelength and to a second spectrum with a second center wavelength, the second spectrum being inverted relative to the first spectrum and the second center wavelength being different from the first center wavelength, and a receiver to receive the first spectrum and the second spectrum, and to estimate a phase rotation of the second spectrum relative to the first spectrum by comparing a first phase measured from the first spectrum with a second phase measured from the second spectrum.